Runs great for 5 minutes, service engine light comes on and idles hard afterwards

NEVERWRENCHED

MEMBER

1984 BUICK LESABRE

180,000 MILES

It starts kind of hard but will run great for 5 or 10 minutes then the service engine light will come on. After it does the car will idle hard and want to stall while stopped at a red light. No problems while in park just in drive. Just recently started to pop and shake, (the whole car will shake). I don't have any experiences with working on cars so I haven't the slightest idea where to look and would like to diagnose this problem without paying an arm and a leg to get it fixed.